Yeast treating method



Dec. 3, 1940. w. P. ToRRlNGToN YEAST TREATING METHOD Filed oct'. '7, 1959 Patented Dec. 3, 1940 UNITED STATES YEAST TREATINGMETHOD miriam P. Torrington, Newl York, N. Y., assignmto Emulslons Process Corporation, New York N. Y., a corporation of Delaware Application October 7, 1939, Serial No. 298,455

15 Claims.

apparatus of breaking down yeast cells to release the enzymes contained therein. So far as I am aware, the methods there and here disclosed are the only practical ones for preparing yeast material from which the vitamins can be extracted in their active state, because no destructive temperatures or chemical re-agents are employed.`

There are vmany processes of cooking yeast and making extracts or treating with' chemicals, such as acids, in order vto obtain vitamin concentrates, but as some of the vitamins are destroyed by the use of heat or chemicals, it is important that such treatments be avoided in order to secure the f ull benefit of the vitamins intheir natural state,v unaltered and combined in their relation to each other as they are in the yeast. y

My methods produce products capable of concentration by low temperature evaporation or spray drying to obtain whole yeast containing vitamins and enzymes in an unaltered condition without having any live cells'present'for reproduction. This is essential because it permits the lfeeding of the human 'system with a 'product which will not cause further growth of the yeast within the digestive tract. It is also important because malt beverages, for example, can be reinf orced with such vitamin extracts without causing any further fermentation dueto the absence of active yeast cells.

Inr my prior application I have disclosed a4 method in which an' aqueous solution of active yeast is subjected to carbonation by dispersing within the same a gas, such `as CO: that will Aprovide an acid reaction V'in connection' with water and that has a. relatively high solubility.-

so that an excess of gas is present in the solution. Subsequently, the solution is subjected to high superatmospheric pressure and to an indenly released to effect expansion of the gas and rupturing of the yeast cells.

The primary purpose of the present invention is to furnish an improved method and apparatus of treating yeast cells so as to alter their permeability or destroy the cell membrane, thereby making available the vitamin B complexes vcontained within the cells.

A further object is to lmwide a method by which concentrated crude extracts of vitamin B creasing temperature before the pressure is sudcomplexes may be cheaply manufactured, and which can be used as a raw material for the manufacture of pure concentrates or as a cheap source of such complexes, 'having the advantage that the B complexes canfbe taken orally without 5 the unpleasant taste `and bulk present when untreated yeast is consumed.

Further work along the line of myoriginal in-l vention has developed several factors of importance. In the nrst place,-I have found that 10 the length of time that the yeast is in contact with CO2 or its equivalent 'is essential. Apparently by maintaining the yeast in contact with the gas under pressure for an extended period of time, vcarbonio acid is formed proportionately to 15 the temperature and pressure under which the yeast is held. As a result of the'acid condition present, through proper control oi these factors, a certain amount oi acid hydrolysis of the yeast cell takes place, with the resulting swelling of 20 the colloidal material within the yeast cell thereby eifectively charging the cell with C02 at the pressure andtemperature at which the solution is stored.

While my improved method may be practiced 25 with various types of apparatus, I have devised a. special apparatus for my purpose, which is illustrated in the accompanying drawing, in

which Fig. 1 is a side elevationof the first portion ofl 30 the apparatus.

Fig. 1a is a similar view of the second portion of the apparatus with a part'in section to facilitate illustration.

Referring to the drawing, 2 designates a tank, 35 3 a pump, 4 a cooler, 5 a dispersion unit `or emulsifying mill, 6 a storage tank for C0: or its equivalent, 6a apressure storage tank, 1 a high pressure pump, 8 'a tubular type heater, 8 a vacuum tank, I0 a vacuum pump, Il a` second 4g tank for CO2 or -the like, and I2 a. compressor.

The aqueous solution of yeast to be treatedv is introduced into' the tank 2 through the pipe I3 or such solution may be introduced directly into the pipe I6 which conveys the same to the pump 45 3. The latter puts the solution under superatmospherlc pressure, say about pounds per square inch, before forcing it through a. pipe l1 linto the cooler I which its temperature is reduced to about 0C., for example.A A

From the cooler, the solution is conducted by a pipe i8 to the dispersion mill 5, which is preferably of the type disclosed in the patent to M. W. Ditto, No. 2,169,339, dated August 15, 1939. As it enters the dispersion lmit, it is mixed with 5| CO2 or its equivalent, which is passed from the tank 6 to the inlet of the vdispersion mill by means of a pipe I9. Inthe mill, the CO: or the like is nely dispersed in the aqueous yeast solution, and the mixture is discharged through a pipe 20 that conveys the same to the pressure tank 6a in which it is maintained for a prolonged period of time under such superatmospheric pressure and temperature, say for a number of hours. After the desired period of storage, the mixture is withdrawn from the tank 6a through the line 20a to the high pressure pump 1 which raises thel pressure on the mixture to a pressure ranging, for example, between 20 and '70 atmospheres, before the mixture travels through a pipe 2| into one end of the tubular heater 8.

is withdrawn from the latter by means o! `the compressor I2 which places it under a'pressure in excess of that used in the dispersion unit 5 so that it may be returned to the tank 6 through the pipe 28 and be passed from the tank 6 into the dispersion unit. I

From the tank 9 the treated yeast solution may be-withdrawn through a pipe 29 and passed .to filters, evaporators, spray dryers, etc. l

'In one method of operation, I take an aqueous solution of brewers yeast and disperse CO: within the same before placing the mixture in the tank 6a and maintaining the mixture in that tank under proper conditions of time, temperature and pressure before increasing the pressure on the mixture, raising its temperature and then spraying the same into the vacuum chamber 9.

Tests have shown that storage of the carbonated yeast solution in the tank 8a under a pressure of approximately ten atmospheres at 0 C. gives satisfactory results over a time period of from 48 to '72 hours.

After such storage the solution was pumped through the heating coil 8 in which its temperature was raised to approximately 30 C. to 49 C. and then sprayed through the nozzle 2l at a pressure of from 20 to 70 atmospheres, into the chamber 9 maintained under from 12 to 20 inches of vacuum.

The combination of absorption of the acid solution through the semi-permeable membrane of heating, to put the CO2 in a gaseous state under the pressure at which it is sprayed through the nozzle, resulted in an extremely vviolent expansion of the CO2 in the vacuum chamber. The CO2 contained within the cell cannot be diiused throughthe membrane slowly as it entered as a weak acid solution, therefore, disintegration `of. the cell wall occurred in some instances and altering of the cell wall to the extent that its permeability is destroyed, occurred in approximately 95% or more of the cells.

It is therefore clear from such tests that after the yeast solution has been held at a given pressure for a sufllcient time, the volume of CO'.` disandthe third sample, sprayed fr0m`1500V pounds solved is a function of the temperature; the weight of the dissolved gas being dependen-t upo dissolved at the higher temperature.

In other Words, when yeast has been in contact with CO2 at a given temperature and pressure and is then heated before spraying, the pressure necessary to maintain the dissolved gas weight is a function of the weight of CO2 dissolved at the storage temperature and pressure over the weight 15 dissolved at the same pressure at the temperature ofthe heating coil. This gives the increase of pressure necessary to hold` the gas in solution.

For example: If yeast solution is stored for va .period of from 48 to 72 hours in contact with CO2 20 at 10 atmospheres absolute `and 0 C., it will absorb 17.13 gvolumes of CO2. If this solution is then passed through a heating coil and the temperature raised to 40 C. the pressure will have to be raised to above 30 atmospheres absolute to 25 hold the gas in solution until it reaches the spray nozzle.

It can easily be seen for every different storage pressure and temperature and change of heating coil temperature, the spray pressure will vary 30 directly as set forth. 1

vI'liere are certain limitations of pressure, as .l storage at 20 atmospheres 0 C. will give 34.26 volumes of CO: which are sufdcient to break down any cells. Also at this volume of CO2 the spray- 35 ing pressure at 40"A C. would be above 67 atmospheres.

The temperature limitations are for storage 0 C. and for spraying between 30.96 C. which is vthe critical temperature for CO2 above which it is o kperiods of time and that as a result of this storage,penetration of the cell and swelling of the cell is secured because of the acid nature of the carbonio acid solution present. Furthermore, the specific fact of spraying this material into a vacuum has a markedly beneficial effect, as microphotographs of samples given the same treatment in which one sample was removed after 72 hours from the bottom of the storage tank showed, as a result of the hydrolysis and release of pressure. just from the mere fact -of taking the sample from the bottom of the tank under pressure, indi'- cation of some 'disintegration yand marked' eyidence of swelling. The second sampley that was sprayed from 1500 pounds into atmospheragave further evidence of more marked disintegration,

into vacuum showed at. least 95% alteration, based upon-a morphological examination with safranin..

The cracked or altered material is the first' step toward recovering the various/valuable constituents contained within the cell, and-I will now disclose various methods by whichconcentrates .or pure products may 4be manufactured' from this' cracked or altered material.

It well known .thatiyeastfisa veryyaluable source of vitamin B complexes and the amount of vitaminB present, is controlled by the nutrient solution in which the yeast was raised. Bakers yeast which ordinarilyis raised in nutrient slutions deiicient in the vitamin complexes, contains but small amounts of these vitamins. On the other hand, brewers yeastY contains large amounts of all of the vitamin B complexes known today. 'I'his is'due to the fact that malted grain used'is very rich in these vitamins and that the yeast has the peculiar property of taking up such vitamins andl storing them within the cell to be used in its own metabolism. As a result, beer produced today (that is'iltered of all yeast cells) shows no traces of the vitamin complexes. Tests 'of American brewers yeast show that it contains 50 to 60 Sherman umts oivitamin-B-l per gram and about'50 to 60 *international units vitamins B--2 or G per gram. When onev compares this vitamin potency, which is approximately 1800 international units per ounce, with wheat germ which contains about 190A international unitsper ounce, it can be readily seen that brewers yeast is one of the most valuable sources of Vraw material for obtaining vitamin B complexes.

Many methods have been proposed for separat ing the vitamins `from brewers yeast,'in all of which endeavors have been made to break down thecell wall so as to release the water soluble vitamin material contained within the cell. 'I'here are two main components of these vitamin B complexes, one being thermo-labile and consisting of B-l or tl'iialnin---B-BV and B-4, and other unknown complexes 4of Athis type. d These are affected to a considerable extent by heating and particularly by alkalis. Weak acids appar; ently have no effect'. Of the thermo-stable components, there are riboilavin, nicotinic acid, B-6, and other unknown complexes. While these compounds are relatively stable to heat they are affected by alkalis but apparently are stable to weak acids.

At the present time vitamin B-l or thiamin, vitamin 13 2` which is lriboilavin, nicotinic acid, B6, the rat acroydnia factor, have been isolated and synthesized. vInvestigations have shown the presence of Ymany physiologically active water soluble substances beside these, of which. B-3, B-4 and B-5 are speci'cally known. There are still many other of these B complexes that are known to exist but whosev speciiic action has not yet been determined.

In the treatment of many nutritional vitamin deficiencies it is of advantage to use a vitamin B complex extract that has been concentrated, (so that large dosage is not necessary) in preference to using thiamin or other pure principals unless a diagnosis has .been made showing that there has been a lackof one particular vitamin such as in polyneuritis, beri-beri or pellagra.l

Therefore, by my process I can alter the permeability of the cell wall of the yeast Without the use of heat or chemicals with the exception of a very Weak solution of carbonic acid and in- .asmuch as CO2 is one of the products of the metabolism of the yeast cell, vand the B complexesare all stable to weak acids, I can prepare a material from Whichby water extraction andcentrifuge or filtering, the vitamin B complexes can effectively be removed. The concentration is a simple matter and can be carried out by means of reduction to a syrup under vacuum or spray drying into a powder. This material can be useddirectly as vitamin B complex concentrate for nutritional correction or can be used as a raw stock for subsequent separation through the many well known methods for the manufacture of pure principals. teri-al is that the-cracked or altered yeast can be addedto the fermenting tanks, of brewers or distillers and will very markedly increase the rateo! fermentationdue to the Vitamins present-see page 374, Vitamin B-1, Williams and Spies.)v y

After the Water extraction is completed, the pressed cell debris may be spray dried and sold for tood purposes or it may be the. basis for the extraction of ergosterol To avoid undue dilution of the yeast it is pref.r

erably handled in a viscous or plasticcondition, and until the cell, has been broken down, remains in Ythat state. When such a plastic mass is treated (Another valuable use of this maby myfprocess,V the :fluidity ofthe product is greatly increased so that it iseasier. to handle.

Previous to the processing the cell mass of the yeast will stratify or segregate in water solutionsV solubility Would'duplicate the conditions securedv with the use of CO2. It will therefore be understood that I propose to use in my process any suitable gas capable of an'ecting the cells to produce the desired result, and which upon heating and discharging' from high pressure into a vacuum, will cause the desired rupturing of the cell.'

From the foregoing it will be understood that prolonged contact of the aqueous yeast `solution with CO2 or its equivalent under pressureis advantageous, as swelling ofthe cell is caused, and beneficial eiects'are secured through discharging the treated solution into a. vacuum zone. The

material produced in this manner is a Valuable source of vitamin B complexes, and extracts of the same can be made by. using various wellknown methods of separation. These crude ex-y tracts can be spray dried 'and used, or they can be the raw material from which the pure active principals can be extracted by Well known means. I also recognize the fact that if this cracked or altered yeast or its extracts are added to fer,- menting yeast, it will accelerate the fermentation rate. I am also aware that these extracts, concentrated or otherwise, can be added to finished malt beverages, suchlas beer, so that the beverage will contain thevarious vitamin B complexes to assist in the carbohydrate metabolism. -Due to the fact that this treatmentfalters or disintegrates the yeast cells, the product can be packed in containers andshipped in the liquid state Without gas formation such as takes place with v ordinary liquid yeast.

Instead of dispersion CO2 or its equivalent alone in the aqueous yeast solution I may dilute the gas with air or oxygen prior to suchdispersion.

The invention is capableA of various modifications and changes, all of which are comprehended Within the scope of the appended claims.

What I claim and desire tosecure by Letters Patent is: y

l. In a process of the character described, dispersing CO2 in an aqueous yeast solution, maintaining the mixture at suhatmospheric temperatures and superatmospheric pressures `for a proi longed period of time, then subjecting the mixi proximately .said temperature and pressure( for a prolonged period of time, and then subjectingthe mixture to a high superatmospheric pressure and vsuperatmospheric temperature up to approximately 49 C., and finally releasing the pressure and introducing the mixture into a subatmospheric zone where the gas separates from the solution.

3. In a process of the character described, dispersing 'CO2 in an aqueous yeast solution at a pressure of the order of pounds per square inch and at suhatmospheric temperature, -maintaining the mixture at substantially said temperature and pressure for a prolonged period of time, then subjecting the mixture to a highl superatmospheric pressure and superatmospheric.

temperature up to approximately 49 C., and finally releasing the pressure' and introducing the mixture into a suhatmospheric zone where the gas separates from the solution.

4, In a process of the character described, dispersing CO2 in an `aqueous solution of brewers yeast, then maintaining the mixture at subatmospheric temperatures and superatmospheric pressures for a prolonged period of time, then'.

subjecting the mixture to a high superatmospheric pressure and superatmospheric temperature up to approximately 49 C., and iinally releasing thel pressure and introducing the -mixture into a suhatmospheric zone where the gas separates from th'e solution.

5.v In a process of the character described, dispersing' CO2 in an aqueous yeast solution at superatmospheric pressure and suhatmospheric temperatures, 4maintaining the mixture at substantially said temperatures and pressures for a prolonged period of time, then subjecting the mixture to superatmospheric temperature from about .30 C. to approximately 49 C. and a pressure above ten atmospheres, and nally releasing the pressure and introducing the mixture into a suhatmospheric zone where. the gas separates from the solution.

6. In a process of the character described, dispersing CO2 in gaseous condition in an aqueous yeast solution at superatmospheric pressure and suhatmospheric temperature, maintaining the mixture substantially at said temperatures and pressures for a number of-hours, 'then subjecting the mixture to a high superatmospheric'pressure and superatmospheric temperature, rfrom about 30 C. to approximately 49 C., and finally releasing the pressure and introducing the mixture into a suhatmospheric zone Where the gas separates-from the solution. f

7. In a process of the character described, dispersing CO2 in an aqueous yeast solution at superatmospheric pressures and subatmospheric temperatures, maintaining the mixture at such temperatures and pressureffor about 48 to 72 hours, then subjecting' the mixture to a high superatmospheric pressure and superatmospheraaaasoi ic temperature upto approximately 49 C., and nnally releasing the pressure and introducing the mixture into a suhatmospheric zone where the gas separates from the solution.

8. In a. process oi' the character described, dispersing CO2 in an aqueous yeast solution at superatmospheric pressures and subatmospheric temperatures, maintaining the mixture at substantially said .temperatures and pressures for a prolonged period of time, thensubjecting the mixture to a pressure ranging between20 to 'l0 atmospheres and to superatmospheric temperatures up to approximately 49 C., andnally releasing the pressure vand introducing 'the mixture into a subatmospheric zone where the-gas separates from the solution. f

9. In a process of the character described, dispersing CO2 in an aqueous solution at superatmospheric pressures and at subatmospheric temperatures, maintaining the mixture at substantially said temperatures and pressures for a prolonged period. of time, then subjecting themixture to a high superatmospheric pressure and a Atemperature of approximately 30 C.to 49 C., and iinally releasing thefpressure Iand introducing the mixture into a suhatmospheric zone where `lution at superatmospheric pressures and subatmospheric temperatures, maintaining the mixture at substantially said temperatures and pressures and in the absence of any nutrient for a prolonged period of time, then subjecting the mixture to a high superatmospheric pressure and superatmospheric temperature lup to approxil mately 49 C., and finally releasing the pressure and introducing the mixture into a vacuum zone where the gas separates from the solution.

11. InV a process of the character described,

dispersing CO2 in an aqueous yeast solution at' substatnially 0 C. and at a pressure of approximately ten atmospheres, maintaining the mixture'at substantially the same temperatures 'and pressures for a number ofhours, then subjecting the mixture to a high superatmospheric pressure and superatmospheric temperaturev up to.

approximately 49C., and iinally ,releasing the pressure and introducing the mixture into a subatmospheric zone where the gas-separates from the solution.

12. In a .process ,of the character described.

dispersing CO2 in Lan laqueous viscous yeast solution, maintaining the mixture at suhatmospheric temperatures and superatmospheric pressures for a number of hours, then subjecting thev mixture to a high superatmospheric pressure and superatmospheric temperature up to approximately 49 C., and finally releasing the pressure and introducing the mixture into a suhatmospheric zone where the gas separates from the solution.

13. A yeast treating process comprising dispersing CO2 in-a yeast solution, maintaining the mixture under relatively low superatmospheric pressures for at least a day, then subjecting the mixture to a relatively high superatmospheric pressure and superatmospheric temperature up to approximately 49 C., and 'iinallyreleasing the pressure and discharging the mixture into evacuum zone where the gas separates i'rom the s0- lution. n

14. In a process of the character described. dispersing CO2 in gaseous condition in an' aqueous yeast solution maintaining the kmixture at a subatmospheric temperature and a. superatmospheric pressure for a prolonged period of time during which the CO: is in liquid phase, subjecting the mixture at the end of said period to a high superatmospheric pressure and superatmospheric temperature up to approximately 49 C., and'nnally .releasing the pressure and introducing the mixture into a vacuum zone where the gas separates from the solution.

in contact with an aqueous yeast 'solution et subatmospheric temperatures and superctmosplieric pressures for a prolonged perlod of time, then subjecting the mixture to a higher superatmospheric pressure and superatmospheric temperature up to approximately 49 C.. and ilnally releasing the pressure and introducing the mixture into a substantially atmospheric `zone where the gas separates from the solution. l

WILLIAM P. TORRINGTON. 

